[U-Boot] [RFC] fs: make it possible to read the filesystem UUID

[Pavel Machek <pavel@denx.de>]

Hi!

> Adding Stephen Warren, Simon Glass and Pavel Machek to CC list
> (./scripts/get_maintainer.pl -f fs/fs.c).

I'm not really fs maintainer, I added people that might be interested.
> 
> 2014-10-22 15:29 GMT+02:00 Christian Gmeiner <christian.gmeiner@gmail.com>:
> > Some filesystems have a UUID stored in its superblock. To
> > allow using root=UUID=... for the kernel command line we
> > need a way to read-out the filesystem UUID. This is what this
> > patch tries to do.
> >
> > Keep in mind that this patch is an RFC and I hope to get some
> > feedback on this patch.
> >
> > This is what blkid under linux gives me:
> > /dev/sdh1: LABEL="data" UUID="b6995cec-97e2-48b8-94dc-8ba7afc92bac" TYPE="ext4" PARTUUID="43f21f0e-01"
> > /dev/sdh2: LABEL="rfs" UUID="8d020de7-c75e-4674-948e-f7838a931b02" TYPE="ext4" PARTUUID="43f21f0e-02"
> >
> > And here is the output from u-boot:
> > => sata init
> > AHCI 0001.0300 32 slots 1 ports 3 Gbps 0x1 impl SATA mode
> > flags: ncq stag pm led clo only pmp pio slum part
> > SATA Device Info:
> > S/N: 000060059798A1000014
> > Product model number: SFCA4096H1BR4TO-I-MS-236-STD
> > Firmware version: 20111021
> > Capacity: 7793856 sectors
> > => fs_uuid sata 0:1 ; print fs_uuid; fs_uuid sata 0:2 ; print fs_uuid
> > fs_uuid=b6995cec-97e2-48b8-94dc-8ba7afc92bac
> > fs_uuid=8d020de7-c75e-4674-948e-f7838a931b02
> >
> 
> Really no feedback?

I see nothing obviously wrong... But I'm not a fs/ maintainer. We
don't have one, AFICT.

> > Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
> > ---
> >  common/Makefile       |  1 +
> >  common/cmd_fs_uuid.c  | 23 +++++++++++++++++++++++
> >  fs/ext4/ext4_common.c |  9 +++++++++
> >  fs/fs.c               | 28 ++++++++++++++++++++++++++++
> >  include/ext4fs.h      |  1 +
> >  include/fs.h          |  2 ++
> >  6 files changed, 64 insertions(+)
> >  create mode 100644 common/cmd_fs_uuid.c
> >
> > diff --git a/common/Makefile b/common/Makefile
> > index b19d379..d5d3315 100644
> > --- a/common/Makefile
> > +++ b/common/Makefile
> > @@ -188,6 +188,7 @@ obj-y += usb.o usb_hub.o
> >  obj-$(CONFIG_USB_STORAGE) += usb_storage.o
> >  endif
> >  obj-$(CONFIG_CMD_FASTBOOT) += cmd_fastboot.o
> > +obj-$(CONFIG_CMD_FS_UUID) += cmd_fs_uuid.o
> >
> >  obj-$(CONFIG_CMD_USB_MASS_STORAGE) += cmd_usb_mass_storage.o
> >  obj-$(CONFIG_CMD_THOR_DOWNLOAD) += cmd_thordown.o
> > diff --git a/common/cmd_fs_uuid.c b/common/cmd_fs_uuid.c
> > new file mode 100644
> > index 0000000..3af9518
> > --- /dev/null
> > +++ b/common/cmd_fs_uuid.c
> > @@ -0,0 +1,23 @@
> > +/*
> > + * cmd_fs_uuid.c -- fs_uuid command
> > + *
> > + * Copyright (C) 2014, Bachmann electronic GmbH
> > + *
> > + * SPDX-License-Identifier:    GPL-2.0+
> > + */
> > +
> > +#include <common.h>
> > +#include <command.h>
> > +#include <fs.h>
> > +
> > +static int do_fs_uuid_wrapper(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
> > +{
> > +       return do_fs_uuid(cmdtp, flag, argc, argv, FS_TYPE_ANY);
> > +}
> > +
> > +U_BOOT_CMD(
> > +       fs_uuid,        3,      0,      do_fs_uuid_wrapper,
> > +       "filesystem UUDI related commands",
> > +       "<interface> <dev>:<part>\n"
> > +       "    - print filesystem UUID\n"
> > +);
> > diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
> > index 33d69c9..926b6c6 100644
> > --- a/fs/ext4/ext4_common.c
> > +++ b/fs/ext4/ext4_common.c
> > @@ -2246,3 +2246,12 @@ fail:
> >
> >         return 0;
> >  }
> > +
> > +void ext4fs_uuid(char *uuid_str)
> > +{
> > +       if (ext4fs_root == NULL)
> > +               return;
> > +
> > +       uuid_bin_to_str((unsigned char *)ext4fs_root->sblock.unique_id, uuid_str,
> > +                       UUID_STR_FORMAT_STD);
> > +}
> > diff --git a/fs/fs.c b/fs/fs.c
> > index dd680f3..f8c6d64 100644
> > --- a/fs/fs.c
> > +++ b/fs/fs.c
> > @@ -85,6 +85,7 @@ struct fstype_info {
> >         int (*size)(const char *filename);
> >         int (*read)(const char *filename, void *buf, int offset, int len);
> >         int (*write)(const char *filename, void *buf, int offset, int len);
> > +       void (*uuid)(char *uuid_str);
> >         void (*close)(void);
> >  };
> >
> > @@ -113,6 +114,7 @@ static struct fstype_info fstypes[] = {
> >                 .size = ext4fs_size,
> >                 .read = ext4_read_file,
> >                 .write = fs_write_unsupported,
> > +               .uuid = ext4fs_uuid,
> >         },
> >  #endif
> >  #ifdef CONFIG_SANDBOX
> > @@ -206,6 +208,14 @@ static void fs_close(void)
> >         fs_type = FS_TYPE_ANY;
> >  }
> >
> 
> Should I do add an #ifdef CONFIG_CMD_FS_UUID around .uuid = ext4fs_uuid?
> Or speaking more general: At which places should I add this ifdef to
> opt-in the FS_UUID
> feature?

I guess so. And I guess it is worth it to remove ext4fs_uuid function
when !defined(CONFIG_CMD_FS_UUID)...

> > +void fs_uuid(char *uuid_str)
> > +{
> > +       struct fstype_info *info = fs_get_info(fs_type);
> > +
> > +       if (info->uuid)
> > +               info->uuid(uuid_str);
> > +}
> > +
> >  int fs_ls(const char *dirname)
> >  {
> >         int ret;
> > @@ -289,6 +299,24 @@ int fs_write(const char *filename, ulong addr, int offset, int len)
> >         return ret;
> >  }
> >
> > +int do_fs_uuid(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
> > +               int fstype)
> > +{
> > +       char uuid[37];
> > +       memset(uuid, 0, sizeof(uuid));
> > +
> > +       if (argc != 3)
> > +               return CMD_RET_USAGE;
> > +
> > +       if (fs_set_blk_dev(argv[1], argv[2], fstype))
> > +               return 1;
> > +
> > +       fs_uuid(uuid);
> > +       setenv("fs_uuid", uuid);
> > +
> > +       return 0;
> > +}
> > +
> >  int do_size(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
> >                 int fstype)
> >  {
> > diff --git a/include/ext4fs.h b/include/ext4fs.h
> > index 6c419f3..4011370 100644
> > --- a/include/ext4fs.h
> > +++ b/include/ext4fs.h
> > @@ -132,6 +132,7 @@ struct ext_filesystem *get_fs(void);
> >  int ext4fs_open(const char *filename);
> >  int ext4fs_read(char *buf, unsigned len);
> >  int ext4fs_mount(unsigned part_length);
> > +void ext4fs_uuid(char *uuid_str);
> >  void ext4fs_close(void);
> >  void ext4fs_reinit_global(void);
> >  int ext4fs_ls(const char *dirname);
> > diff --git a/include/fs.h b/include/fs.h
> > index 06a45f2..1956b67 100644
> > --- a/include/fs.h
> > +++ b/include/fs.h
> > @@ -82,6 +82,8 @@ int fs_write(const char *filename, ulong addr, int offset, int len);
> >   * Common implementation for various filesystem commands, optionally limited
> >   * to a specific filesystem type via the fstype parameter.
> >   */
> > +int do_fs_uuid(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
> > +               int fstype);
> >  int do_size(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
> >                 int fstype);
> >  int do_load(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
> > --
> > 1.9.3
> >
> 
> Thanks
> --
> Christian Gmeiner, MSc
> 
> https://soundcloud.com/christian-gmeiner

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html